The idea is gaining ground in some circles that an excessively limited strike against Bashar al-Assad's chemical weapons program would undermine U.S. credibility and interests more than would a decision not to strike. On its face, this argument is appealing: After all the buildup and expressions of moral indignation, supporters of intervention would, of course, feel let down by a weak attack. Assad and his Russian and Iranian backers would no doubt declare that they have once again defeated the great superpower. And the media may fill with questions about the United States' strength and determination.

But even a weak strike is more in line with U.S. interests than a refusal to strike or, worse, congressional action blocking any attack. Not just U.S. credibility but also the will of the Syrian opposition is at stake.

Especially after this lengthy buildup and public debate, Syrian rebels and their supporters would view a U.S. failure to act as abandonment of their cause. In particular, the moderate Syrian opposition, which relies on support from the United States and its allies, would be devastated. These people are the majority of the opposition. The al-Qaida franchises that have no expectation of U.S. aid and other terrorists are estimated to comprise 15 percent to 20 percent of Syria's opposition fighters. So at this moment, inaction is likely to strengthen Assad, Iran, Hezbollah and al-Qaida -- and weaken the lone group whose interests coincide with America's at all.

The Washington debate is parsing this issue too finely. At the end of the day, Syrians are going to see one of two things: Either nothing will occur, and they will be left to fight Assad's brutality on their own, or U.S. missiles will explode on military facilities and units flying Assad's flag. Some may be disappointed that larger plumes of smoke are not rising from more Assad facilities, but among Syrian rebels there would be no doubt that the United States had taken their side and hurt their enemy.

And that logic would hold true for Syrians even if U.S. officials then said, no, Washington hasn't taken their side. Rhetoric may be real in Washington, but smoke and debris tell their own story on the ground.

The situation has taken on this cast largely because of the nature of the U.S. debate. If President Barack Obama had not declared the use of chemical weapons a "red line," if he had not said that he intended to punish Assad by using force and if Congress were not now considering a resolution to authorize the president to use force, then an argument for building a more robust domestic and international coalition before launching a more meaningful strike would have some validity. But that series of events and the delays in promised U.S. aid have already caused the opposition to seriously question whether the United States supports them.

Rumors are circulating in Syria that the United States has cut some kind of deal with Assad and secretly wants him to win. From the perspective of a fighter in Damascus, there is logic to that thinking: Obama has said that he wants Assad to go and that he would use force if Assad used chemical weapons. Congress has been pushing for more aid to the opposition. Assad crossed the red line, Obama punted to Congress ... and Congress refuses authorization to attack. How is a rebel leader to make sense of that sequence of events?

"Congress voted to stop the president from attacking Assad because it wanted to hit Assad harder, even though it doesn't really think the president will do so?" How does one convey to a Free Syrian Army fighter that the United States really is on his side when almost all of the amendments to the use-of-force resolution involve limiting the strike, ruling out ground forces, and demanding that the president identify offsetting spending cuts in the defense budget or elsewhere -- and then the bill is still defeated? Internationalists making the case for a stronger response will be more than matched by isolationists delighting in having kept the United States out of "someone else's war." In fact, the isolationist narrative is rapidly becoming dominant. To Syrian fighters, the message will be unambiguous.

A better option, of course, would be a robust strike coupled with meaningful support to the Free Syrian Army. The Obama administration makes a bad mistake by defining both the strike and its justification exclusively in terms of punishing Assad for using chemical weapons and denying that it intends for the strike to alter the balance of power in Syria. The United States has important national interests in weakening Iran's most important ally in the Levant, ensuring that Lebanese Hezbollah's first invasion of another country fails and showing Iran that even the deployment of Revolution Guard training teams cannot save Tehran's proxies.

At this point, either action or inaction will affect the balance. Even weak action would keep hope alive among the opposition. Inaction would probably convince them that they're on their own. This wouldn't be the first time that a U.S. administration has disappointed allies with inadequate support or weak strikes. Although it has generally been possible, over time, to recover from such disappointments by increasing support and other demonstrations of commitment, overcoming the sense of abandonment likely to be instilled by inaction at this point might be impossible.

The president created this sour choice between an inadequate strike and no strike. It is a choice between a bad option and a less bad option. The less bad option is to strike now and continue to push for more robust action as necessary in the future.

That decision demands the support of those who are serious about the outcome in Syria and maintaining U.S. credibility.

Frederick W. Kagan is a scholar at the American Enterprise Institute and director of its Critical Threats Project.

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